Oooh, I like sticking film on. Make sure each piece is cut slightly too large for the glass.
Makeup a bowl of warm water with a small amount of washing up liquid. Have towels on the floor to catch the drips.
Make sure the glass is spotlessly clean and then make it wet with the soapy water. Peel back just the very top corner of the film backing and push into more or less the right place, ensuring that you have a tiny overlap with the frame, just in case the film isn't quite cut straight.
Use the soapiness to let you adjust the positioning as you peel the backing off and, only as you are sure it's in the right positioning, push the water out from underneath using a points card (better than a credit card because it doesn't have your banking details on it - and they're free) starting at one top corner, ensuring all the bubbles and creases are taken out before moving onto the next section. If it's too wet and is sliding about all over the place, use a towel to mop up the very wettest bits.
Work your way down. If you find a crease or bubble/go wrong, add a little more soapy water from underneath.
Tiny bubbles will disappear if you pierce them later, but anything over a tiny dot needs to be unpeeled and flattened at the time.
Use the card to run along the edges and push them into the frame/trim larger excesses by doing that then running a new Stanley blade extremely carefully against the frame (not the glass, as that makes it too easy to cut the bit you want to keep).
Dry it off a couple of times from top to bottom (there will be drips) and if you find a bubble of water, again pricking it with a needle will help it flatten - or a larger one you've missed can be improved vastly by gently slitting it with the Stanley blade, carding from outside to in and mopping up the water with a cloth.
I learned from an ex who had to put huge expanses up on various surfaces, not just glass, as one part of his job.
It's much easier and effective to do it that way than hope you get the sticky back in the right place first time.
(Of course, this is if you are using sticky film and aren't using static cling instead - that, just follow the instructions).